firmware/target/hosted/sdl/thread-sdl.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2006 Dan Everton
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21
  22 #include <stdbool.h>
  23 #include <time.h>
  24 #include <SDL.h>
  25 #include <SDL_thread.h>
  26 #include <stdlib.h>
  27 #include <string.h> /* memset() */
  28 #include <setjmp.h>
  29 #include "system-sdl.h"
  30 #include "thread-sdl.h"
  31 #include "system.h"
  32 #include "kernel.h"
  33 #include "thread.h"
  34 #include "debug.h"
  35
  36 /* Define this as 1 to show informational messages that are not errors. */
  37 #define THREAD_SDL_DEBUGF_ENABLED 0
  38
  39 #if THREAD_SDL_DEBUGF_ENABLED
  40 #define THREAD_SDL_DEBUGF(...) DEBUGF(__VA_ARGS__)
  41 static char __name[32];
  42 #define THREAD_SDL_GET_NAME(thread) \
  43     ({ thread_get_name(__name, ARRAYLEN(__name), thread); __name; })
  44 #else
  45 #define THREAD_SDL_DEBUGF(...)
  46 #define THREAD_SDL_GET_NAME(thread)
  47 #endif
  48
  49 #define THREAD_PANICF(str...) \
  50     ({ fprintf(stderr, str); exit(-1); })
  51
  52 /* Thread/core entries as in rockbox core */
  53 static struct core_entry cores[NUM_CORES];
  54 struct thread_entry threads[MAXTHREADS];
  55 /* Jump buffers for graceful exit - kernel threads don't stay neatly
  56  * in their start routines responding to messages so this is the only
  57  * way to get them back in there so they may exit */
  58 static jmp_buf thread_jmpbufs[MAXTHREADS];
  59 /* this mutex locks out other Rockbox threads while one runs,
  60  * that enables us to simulate a cooperative environment even if
  61  * the host is preemptive */
  62 static SDL_mutex *m;
  63 static volatile bool threads_exit = false;
  64
  65 extern long start_tick;
  66
  67 void sim_do_exit(SDL_mutex *m);
  68
  69 void sim_thread_shutdown(void)
  70 {
  71     int i;
  72
  73     /* This *has* to be a push operation from a thread not in the pool
  74        so that they may be dislodged from their blocking calls. */
  75
  76     /* Tell all threads jump back to their start routines, unlock and exit
  77        gracefully - we'll check each one in turn for it's status. Threads
  78        _could_ terminate via remove_thread or multiple threads could exit
  79        on each unlock but that is safe. */
  80
  81     /* Do this before trying to acquire lock */
  82     threads_exit = true;
  83
  84     /* Take control */
  85     SDL_LockMutex(m);
  86
  87     /* Signal all threads on delay or block */
  88     for (i = 0; i < MAXTHREADS; i++)
  89     {
  90         struct thread_entry *thread = &threads[i];
  91         if (thread->context.s == NULL)
  92             continue;
  93         SDL_SemPost(thread->context.s);
  94     }
  95
  96     /* Wait for all threads to finish and cleanup old ones. */
  97     for (i = 0; i < MAXTHREADS; i++)
  98     {
  99         struct thread_entry *thread = &threads[i];
 100         SDL_Thread *t = thread->context.t;
 101
 102         if (t != NULL)
 103         {
 104             SDL_UnlockMutex(m);
 105             /* Wait for it to finish */
 106             SDL_WaitThread(t, NULL);
 107             /* Relock for next thread signal */
 108             SDL_LockMutex(m);
 109             /* Already waited and exiting thread would have waited .told,
 110              * replacing it with t. */
 111             thread->context.told = NULL;
 112         }
 113         else
 114         {
 115             /* Wait on any previous thread in this location-- could be one not quite
 116              * finished exiting but has just unlocked the mutex. If it's NULL, the
 117              * call returns immediately.
 118              *
 119              * See remove_thread below for more information. */
 120             SDL_WaitThread(thread->context.told, NULL);
 121         }
 122     }
 123
 124     SDL_UnlockMutex(m);
 125 }
 126
 127 static void new_thread_id(unsigned int slot_num,
 128                           struct thread_entry *thread)
 129 {
 130     unsigned int version =
 131         (thread->id + (1u << THREAD_ID_VERSION_SHIFT))
 132             & THREAD_ID_VERSION_MASK;
 133
 134     if (version == 0)
 135         version = 1u << THREAD_ID_VERSION_SHIFT;
 136
 137     thread->id = version | (slot_num & THREAD_ID_SLOT_MASK);
 138 }
 139
 140 static struct thread_entry * find_empty_thread_slot(void)
 141 {
 142     struct thread_entry *thread = NULL;
 143     int n;
 144
 145     for (n = 0; n < MAXTHREADS; n++)
 146     {
 147         int state = threads[n].state;
 148
 149         if (state == STATE_KILLED)
 150         {
 151             thread = &threads[n];
 152             break;
 153         }
 154     }
 155
 156     return thread;
 157 }
 158
 159
 160 /* Initialize SDL threading */
 161 void init_threads(void)
 162 {
 163     struct thread_entry *thread;
 164     int n;
 165
 166     memset(cores, 0, sizeof(cores));
 167     memset(threads, 0, sizeof(threads));
 168
 169     m = SDL_CreateMutex();
 170
 171     if (SDL_LockMutex(m) == -1)
 172     {
 173         fprintf(stderr, "Couldn't lock mutex\n");
 174         return;
 175     }
 176
 177     /* Initialize all IDs */
 178     for (n = 0; n < MAXTHREADS; n++)
 179         threads[n].id = THREAD_ID_INIT(n);
 180
 181     /* Slot 0 is reserved for the main thread - initialize it here and
 182        then create the SDL thread - it is possible to have a quick, early
 183        shutdown try to access the structure. */
 184     thread = &threads[0];
 185     thread->stack = (uintptr_t *)"       ";
 186     thread->stack_size = 8;
 187     thread->name = "main";
 188     thread->state = STATE_RUNNING;
 189     thread->context.s = SDL_CreateSemaphore(0);
 190     thread->context.t = NULL; /* NULL for the implicit main thread */
 191     cores[CURRENT_CORE].running = thread;
 192
 193     if (thread->context.s == NULL)
 194     {
 195         fprintf(stderr, "Failed to create main semaphore\n");
 196         return;
 197     }
 198
 199     /* Tell all threads jump back to their start routines, unlock and exit
 200        gracefully - we'll check each one in turn for it's status. Threads
 201        _could_ terminate via remove_thread or multiple threads could exit
 202        on each unlock but that is safe. */
 203
 204     /* Setup jump for exit */
 205     if (setjmp(thread_jmpbufs[0]) == 0)
 206     {
 207         THREAD_SDL_DEBUGF("Main thread: %p\n", thread);
 208         return;
 209     }
 210
 211     SDL_UnlockMutex(m);
 212
 213     /* doesn't return */
 214     sim_do_exit(m);
 215 }
 216
 217 void sim_thread_exception_wait(void)
 218 {
 219     while (1)
 220     {
 221         SDL_Delay(HZ/10);
 222         if (threads_exit)
 223             thread_exit();
 224     }
 225 }
 226
 227 /* A way to yield and leave the threading system for extended periods */
 228 void sim_thread_lock(void *me)
 229 {
 230     SDL_LockMutex(m);
 231     cores[CURRENT_CORE].running = (struct thread_entry *)me;
 232
 233     if (threads_exit)
 234         thread_exit();
 235 }
 236
 237 void * sim_thread_unlock(void)
 238 {
 239     struct thread_entry *current = cores[CURRENT_CORE].running;
 240     SDL_UnlockMutex(m);
 241     return current;
 242 }
 243
 244 struct thread_entry * thread_id_entry(unsigned int thread_id)
 245 {
 246     return (thread_id == THREAD_ID_CURRENT) ?
 247         cores[CURRENT_CORE].running :
 248         &threads[thread_id & THREAD_ID_SLOT_MASK];
 249 }
 250
 251 static void add_to_list_l(struct thread_entry **list,
 252                           struct thread_entry *thread)
 253 {
 254     if (*list == NULL)
 255     {
 256         /* Insert into unoccupied list */
 257         thread->l.next = thread;
 258         thread->l.prev = thread;
 259         *list = thread;
 260     }
 261     else
 262     {
 263         /* Insert last */
 264         thread->l.next = *list;
 265         thread->l.prev = (*list)->l.prev;
 266         thread->l.prev->l.next = thread;
 267         (*list)->l.prev = thread;
 268     }
 269 }
 270
 271 static void remove_from_list_l(struct thread_entry **list,
 272                                struct thread_entry *thread)
 273 {
 274     if (thread == thread->l.next)
 275     {
 276         /* The only item */
 277         *list = NULL;
 278         return;
 279     }
 280
 281     if (thread == *list)
 282     {
 283         /* List becomes next item */
 284         *list = thread->l.next;
 285     }
 286
 287     /* Fix links to jump over the removed entry. */
 288     thread->l.prev->l.next = thread->l.next;
 289     thread->l.next->l.prev = thread->l.prev;
 290 }
 291
 292 unsigned int thread_get_current(void)
 293 {
 294     return cores[CURRENT_CORE].running->id;
 295 }
 296
 297 void switch_thread(void)
 298 {
 299     struct thread_entry *current = cores[CURRENT_CORE].running;
 300
 301     enable_irq();
 302
 303     switch (current->state)
 304     {
 305     case STATE_RUNNING:
 306     {
 307         SDL_UnlockMutex(m);
 308         /* Any other thread waiting already will get it first */
 309         SDL_LockMutex(m);
 310         break;
 311         } /* STATE_RUNNING: */
 312
 313     case STATE_BLOCKED:
 314     {
 315         int oldlevel;
 316
 317         SDL_UnlockMutex(m);
 318         SDL_SemWait(current->context.s);
 319         SDL_LockMutex(m);
 320
 321         oldlevel = disable_irq_save();
 322         current->state = STATE_RUNNING;
 323         restore_irq(oldlevel);
 324         break;
 325         } /* STATE_BLOCKED: */
 326
 327     case STATE_BLOCKED_W_TMO:
 328     {
 329         int result, oldlevel;
 330
 331         SDL_UnlockMutex(m);
 332         result = SDL_SemWaitTimeout(current->context.s, current->tmo_tick);
 333         SDL_LockMutex(m);
 334
 335         oldlevel = disable_irq_save();
 336
 337         if (current->state == STATE_BLOCKED_W_TMO)
 338         {
 339             /* Timed out */
 340             remove_from_list_l(current->bqp, current);
 341
 342 #ifdef HAVE_WAKEUP_EXT_CB
 343             if (current->wakeup_ext_cb != NULL)
 344                 current->wakeup_ext_cb(current);
 345 #endif
 346             current->state = STATE_RUNNING;
 347         }
 348
 349         if (result == SDL_MUTEX_TIMEDOUT)
 350         {
 351             /* Other signals from an explicit wake could have been made before
 352              * arriving here if we timed out waiting for the semaphore. Make
 353              * sure the count is reset. */
 354             while (SDL_SemValue(current->context.s) > 0)
 355                 SDL_SemTryWait(current->context.s);
 356         }
 357
 358         restore_irq(oldlevel);
 359         break;
 360         } /* STATE_BLOCKED_W_TMO: */
 361
 362     case STATE_SLEEPING:
 363     {
 364         SDL_UnlockMutex(m);
 365         SDL_SemWaitTimeout(current->context.s, current->tmo_tick);
 366         SDL_LockMutex(m);
 367         current->state = STATE_RUNNING;
 368         break;
 369         } /* STATE_SLEEPING: */
 370     }
 371
 372     cores[CURRENT_CORE].running = current;
 373
 374     if (threads_exit)
 375         thread_exit();
 376 }
 377
 378 void sleep_thread(int ticks)
 379 {
 380     struct thread_entry *current = cores[CURRENT_CORE].running;
 381     int rem;
 382
 383     current->state = STATE_SLEEPING;
 384
 385     rem = (SDL_GetTicks() - start_tick) % (1000/HZ);
 386     if (rem < 0)
 387         rem = 0;
 388
 389     current->tmo_tick = (1000/HZ) * ticks + ((1000/HZ)-1) - rem;
 390 }
 391
 392 void block_thread(struct thread_entry *current)
 393 {
 394     current->state = STATE_BLOCKED;
 395     add_to_list_l(current->bqp, current);
 396 }
 397
 398 void block_thread_w_tmo(struct thread_entry *current, int ticks)
 399 {
 400     current->state = STATE_BLOCKED_W_TMO;
 401     current->tmo_tick = (1000/HZ)*ticks;
 402     add_to_list_l(current->bqp, current);
 403 }
 404
 405 unsigned int wakeup_thread(struct thread_entry **list)
 406 {
 407     struct thread_entry *thread = *list;
 408
 409     if (thread != NULL)
 410     {
 411         switch (thread->state)
 412         {
 413         case STATE_BLOCKED:
 414         case STATE_BLOCKED_W_TMO:
 415             remove_from_list_l(list, thread);
 416             thread->state = STATE_RUNNING;
 417             SDL_SemPost(thread->context.s);
 418             return THREAD_OK;
 419         }
 420     }
 421
 422     return THREAD_NONE;
 423 }
 424
 425 unsigned int thread_queue_wake(struct thread_entry **list)
 426 {
 427     unsigned int result = THREAD_NONE;
 428
 429     for (;;)
 430     {
 431         unsigned int rc = wakeup_thread(list);
 432
 433         if (rc == THREAD_NONE)
 434             break;
 435
 436         result |= rc;
 437     }
 438
 439     return result;
 440 }
 441
 442 void thread_thaw(unsigned int thread_id)
 443 {
 444     struct thread_entry *thread = thread_id_entry(thread_id);
 445
 446     if (thread->id == thread_id && thread->state == STATE_FROZEN)
 447     {
 448         thread->state = STATE_RUNNING;
 449         SDL_SemPost(thread->context.s);
 450     }
 451 }
 452
 453 int runthread(void *data)
 454 {
 455     struct thread_entry *current;
 456     jmp_buf *current_jmpbuf;
 457
 458     /* Cannot access thread variables before locking the mutex as the
 459        data structures may not be filled-in yet. */
 460     SDL_LockMutex(m);
 461     cores[CURRENT_CORE].running = (struct thread_entry *)data;
 462     current = cores[CURRENT_CORE].running;
 463     current_jmpbuf = &thread_jmpbufs[current - threads];
 464
 465     /* Setup jump for exit */
 466     if (setjmp(*current_jmpbuf) == 0)
 467     {
 468         /* Run the thread routine */
 469         if (current->state == STATE_FROZEN)
 470         {
 471             SDL_UnlockMutex(m);
 472             SDL_SemWait(current->context.s);
 473             SDL_LockMutex(m);
 474             cores[CURRENT_CORE].running = current;
 475         }
 476
 477         if (!threads_exit)
 478         {
 479             current->context.start();
 480             THREAD_SDL_DEBUGF("Thread Done: %d (%s)\n",
 481                               current - threads, THREAD_SDL_GET_NAME(current));
 482             /* Thread routine returned - suicide */
 483         }
 484
 485         thread_exit();
 486     }
 487     else
 488     {
 489         /* Unlock and exit */
 490         SDL_UnlockMutex(m);
 491     }
 492
 493     return 0;
 494 }
 495
 496 unsigned int create_thread(void (*function)(void),
 497                            void* stack, size_t stack_size,
 498                            unsigned flags, const char *name)
 499 {
 500     struct thread_entry *thread;
 501     SDL_Thread* t;
 502     SDL_sem *s;
 503
 504     THREAD_SDL_DEBUGF("Creating thread: (%s)\n", name ? name : "");
 505
 506     thread = find_empty_thread_slot();
 507     if (thread == NULL)
 508     {
 509         DEBUGF("Failed to find thread slot\n");
 510         return 0;
 511     }
 512
 513     s = SDL_CreateSemaphore(0);
 514     if (s == NULL)
 515     {
 516         DEBUGF("Failed to create semaphore\n");
 517         return 0;
 518     }
 519
 520     t = SDL_CreateThread(runthread, thread);
 521     if (t == NULL)
 522     {
 523         DEBUGF("Failed to create SDL thread\n");
 524         SDL_DestroySemaphore(s);
 525         return 0;
 526     }
 527
 528     thread->stack = stack;
 529     thread->stack_size = stack_size;
 530     thread->name = name;
 531     thread->state = (flags & CREATE_THREAD_FROZEN) ?
 532         STATE_FROZEN : STATE_RUNNING;
 533     thread->context.start = function;
 534     thread->context.t = t;
 535     thread->context.s = s;
 536
 537     THREAD_SDL_DEBUGF("New Thread: %d (%s)\n",
 538                       thread - threads, THREAD_SDL_GET_NAME(thread));
 539
 540     return thread->id;
 541 }
 542
 543 #ifndef ALLOW_REMOVE_THREAD
 544 static void remove_thread(unsigned int thread_id)
 545 #else
 546 void remove_thread(unsigned int thread_id)
 547 #endif
 548 {
 549     struct thread_entry *current = cores[CURRENT_CORE].running;
 550     struct thread_entry *thread = thread_id_entry(thread_id);
 551
 552     SDL_Thread *t;
 553     SDL_sem *s;
 554
 555     if (thread_id != THREAD_ID_CURRENT && thread->id != thread_id)
 556         return;
 557
 558     int oldlevel = disable_irq_save();
 559
 560     t = thread->context.t;
 561     s = thread->context.s;
 562
 563     /* Wait the last thread here and keep this one or SDL will leak it since
 564      * it doesn't free its own library allocations unless a wait is performed.
 565      * Such behavior guards against the memory being invalid by the time
 566      * SDL_WaitThread is reached and also against two different threads having
 567      * the same pointer. It also makes SDL_WaitThread a non-concurrent function.
 568      *
 569      * However, see more below about SDL_KillThread.
 570      */
 571     SDL_WaitThread(thread->context.told, NULL);
 572
 573     thread->context.t = NULL;
 574     thread->context.s = NULL;
 575     thread->context.told = t;
 576
 577     if (thread != current)
 578     {
 579         switch (thread->state)
 580         {
 581         case STATE_BLOCKED:
 582         case STATE_BLOCKED_W_TMO:
 583             /* Remove thread from object it's waiting on */
 584             remove_from_list_l(thread->bqp, thread);
 585
 586 #ifdef HAVE_WAKEUP_EXT_CB
 587             if (thread->wakeup_ext_cb != NULL)
 588                 thread->wakeup_ext_cb(thread);
 589 #endif
 590             break;
 591         }
 592
 593         SDL_SemPost(s);
 594     }
 595
 596     THREAD_SDL_DEBUGF("Removing thread: %d (%s)\n",
 597         thread - threads, THREAD_SDL_GET_NAME(thread));
 598
 599     new_thread_id(thread->id, thread);
 600     thread->state = STATE_KILLED;
 601     thread_queue_wake(&thread->queue);
 602
 603     SDL_DestroySemaphore(s);
 604
 605     if (thread == current)
 606     {
 607         /* Do a graceful exit - perform the longjmp back into the thread
 608            function to return */
 609         restore_irq(oldlevel);
 610         longjmp(thread_jmpbufs[current - threads], 1);
 611     }
 612
 613     /* SDL_KillThread frees the old pointer too because it uses SDL_WaitThread
 614      * to wait for the host to remove it. */
 615     thread->context.told = NULL;
 616     SDL_KillThread(t);
 617     restore_irq(oldlevel);
 618 }
 619
 620 void thread_exit(void)
 621 {
 622     remove_thread(THREAD_ID_CURRENT);
 623 }
 624
 625 void thread_wait(unsigned int thread_id)
 626 {
 627     struct thread_entry *current = cores[CURRENT_CORE].running;
 628     struct thread_entry *thread = thread_id_entry(thread_id);
 629
 630     if (thread_id == THREAD_ID_CURRENT ||
 631         (thread->id == thread_id && thread->state != STATE_KILLED))
 632     {
 633         current->bqp = &thread->queue;
 634         block_thread(current);
 635         switch_thread();
 636     }
 637 }
 638
 639 int thread_stack_usage(const struct thread_entry *thread)
 640 {
 641     return 50;
 642     (void)thread;
 643 }
 644
 645 /* Return name if one or ID if none */
 646 void thread_get_name(char *buffer, int size,
 647                      struct thread_entry *thread)
 648 {
 649     if (size <= 0)
 650         return;
 651
 652     *buffer = '\0';
 653
 654     if (thread)
 655     {
 656         /* Display thread name if one or ID if none */
 657         bool named = thread->name && *thread->name;
 658         const char *fmt = named ? "%s" : "%08lX";
 659         intptr_t name = named ?
 660             (intptr_t)thread->name : (intptr_t)thread;
 661         snprintf(buffer, size, fmt, name);
 662     }
 663 }